Are there any medications that can be prescribed for a child with attachment problems?

Not usually. This is a big "it depends" type question. If the child is simply having a straight- up problem letting go, transitioning, and bonding with others, then no. It's a matter of conditioning, and likely play therapy. If there's a co-morbid condition such as anxiety, ptsd, or autistic tendencies, then sometimes meds can aid in a comprehensive therapy. Consult with your doctor to see if something's amiss.
Not really. Attachment problems are quite complex. If your psychologist thinks there are comorbidities, then medication may be indicated.